In the nation's capital, 4 to 7 inches of snow fell overnight and the three major airports serving the area, Reagan National, Dulles and Baltimore, saw over 700 flights canceled Sunday alone, according to FlightAware.com. An additional 764 flights were scrubbed into and out of the U.S. on Friday and Saturday.

North Carolina's Gov. Roy Cooper declared a state of emergency on Sunday. In a news release, Cooper said almost 1,000 N.C. Department of Transportation workers were clearing snow and ice in the western part of the state and in the Greensboro area. Work was also concentrated in counties along the Virginia border and in the northern coastal area, Cooper said.

13 People Killed in the Storm

Illinois State Police Trooper Christopher Lambert, 34, was driving home from work Saturday when he stopped to help at a three-car crash on I-294 in Glenview, the Chicago Sun Times reported. Lambert was hit by a passing vehicle about 4:45 p.m., Illinois State Police Director Leo P. Schmitz said at a news conference. The driver who hit Lambert stopped, Schmitz said. The crash appeared to be an accident but was still under investigation.

Illinois State Police also said a Troy, Illinois, man was killed about 5 p.m. Friday when he lost control of his vehicle and crossed into oncoming traffic, striking a van, as he drove east on U.S. Highway 40 in Madison County, KSDK-TV reported. Allen Reinacher, 73, was pronounced dead at the scene. He was not wearing a seat belt. A woman and three passengers in the van he struck were taken to St Joseph’s Hospital in Highland with non life-threatening injuries.

Virginia State Police say the storm contributed to the crash shortly before 9 p.m. Saturday of a military surplus vehicle on Interstate 81 in Pulaski County that killed Ronald W. Harris, 73, of Gainesville, Georgia, the Associated Press reported. The tractor-trailer drivers were taken to a hospital.

At 4:10 a.m. Sunday in Brunswick County, a 16-year-old boy from Alberta, Virginia, died after a pickup truck driven by another 16-year-old lost control on an icy bridge and hit a tree, the Richmond Times-Dispatch reported. The driver was taken to a hospital with life-threatening injuries. Police said speed and alcohol were factors.

Another woman, Hope Wilson, 32, of Carrollton, died about 3 p.m. Friday when her car slid on U.S. 24 in northern Missouri and was hit by an oncoming SUV, KMZU reported. The passenger of the SUV was taken to the hospital with moderate injuries.

Another crash involving two semitrailers in snowy conditions killed a 41-year-old driver from Mexico, the state patrol said.

Stuck on Snowy Interstates For Hours

In a Saturday morning tweet, Missouri Gov. Mike Parson expressed concern and urged all residents to stay off the roads until conditions improved.

The northbound lanes of Interstate 65 in northern Indiana were closed for hours Saturday after a semi-trailer jackknifed along the snow-covered highway about 65 miles northwest of Indianapolis. By about 1 p.m., state troopers had responded to 100 crashes, Indiana State Police Sgt. John Perrine told the Indianapolis Star. In addition to I-65, portions of I-70 and northbound I-465 were closed at various times Saturday.

On Friday, more than 800 motorists became stranded during rush hour as falling snow made Missouri's Interstate 44 virtually impassable.

The Weather Channel's Jim Cantore, reporting Saturday morning from the interstate west of St. Louis, noted that many people remained stuck in conditions he called "horrible."

Some interstates in Missouri, including I-70 and I-44, reopened Saturday morning after being shutdown Friday night, but treacherous conditions continued.

Planes Slide Off Runways

On Friday afternoon, a plane slid off the runway after landing at Columbia Regional Airport in Columbia, Missouri, Rob Quinn tweeted shortly before 3:30 p.m. EST.

"Plane tipped - wing almost hitting the ground. ... I’m on exit row. Bus coming to get us. Stewardess just announced 'congratulations on surviving your first plane crash,'" he said in a tweet.

KOMU-TV reported the plane was American Airlines Flight 5766 from Dallas. The station said passenger Theresa Cook said there were no injuries. A bus sent to take passengers from the plane got stuck, and passengers had to be driven to the terminal three at a time.

Part of the roof of the Canine Sports Center in Columbia, Missouri, collapsed on Saturday, KMZU reported. Firefighters said the weight of snow on the roof may have been the cause.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.